Johnson voices support for May as she vows to press on

"It's about getting the Brexit deal right, it's about building that deep and special partnership with the European Union, but it's also about building global Britain, trading around the world".

May's comments, on an official visit to Japan, prompted despair among some Tory backbenchers, however, and could increase the likelihood of a move against her as soon as Brexit negotiations have been concluded.

The Prime Minister also secured the crucial endorsement of Graham Brady, the chairman of the 1922 Committee of Tory MPs.

In a series of television interviews last night Mrs May insisted she was "not a quitter" and said she wanted to lead the Conservatives into another election, saying: "I'm in this for the long term".

After being bruised this year when May called an early election only to see her party lose its parliamentary majority, several said keeping the party in power was the main priority.

The London Evening Standard, now edited by George Osborne, the Conservative sacked by May as finance minister when she became prime minister past year, described her pledge to run again as "Like the Living Dead in a second-rate horror film".

"We have got to think about how we renew our franchise", she told the BBC.

Margaret Thatcher was a month from leading the Conservatives to their third election victory when she produced one of her most famous phrases.

"It's not about asserting yourself in this way because actually that just winds a lot of people up".

"Yes, there has been an very bad lot of speculation about my future which has no basis in it whatsoever", she told Dinnen, adding: "I'm in this for the long term".

The former told the BBC her performance would be assessed post-Brexit, while the latter - admitting that Theresa May could have said little else in response to questions about her future - believes she still won't lead the party into the next election.

She hoped to silence weeks of media reports that she could leave office as early as the annual party conference in October, an event where political careers have been made or broken in the past. The opposition Labour Party, meanwhile, picked up dozens of seats.

Jeremy Corbyn's party hit 43 per cent in the Survation survey, which was carried out in the week Theresa May pledged to fight the general election, due in 2022.

When asked if she meant to lead the Tories into the next election, May responded: "Yes".

Many of Mrs May's Cabinet members are thought to be starting to jockey to replace her.

"And you can't jump straight from that to "I'll go on forever", you've got to have an in between stage".